Safety valve for electric switches



His Attorney.

Feb- 10, 1931. J. D. HILLIARD v SAFETY. VALVE FOR ELECTRIC SWITCHESFiled oct. 1, 1926 y Patented Feb. l0, 1931 UNITE-D sTai*as*l COMPANY, AcoiaroRA'rroN oiiNEw ironia,Z

SAFETY VALVE Fon. annemarie.; :swiiiciinsj Application ined october1,1926. 'seriaiiva 138,371. i'

My invention relates to electric switches and particularly to switchesof the fluid break type whereinthe contacts separate beneath the surfaceof an insulating' fluid. Wlheii anl lti arc is drawn in insulatingfluids commonly used in such switches a certain amount of gas is formeddue principally to the decomposition of the liquid, the amount dependingupon the value of the current and voltage interrupted and the length oftime that thearc continues. In ordinary use the amount of gaspressuregenerated in the switch is not excessive, the gas being commonly ventedi through a relatively small orifice and may be lr5rconducted away whereit can do no harm.

If, however, an accidental breakdown should occur in the switch such asto cause a con* tinuous arcing under short circuit conditions theV gaswould be generated at such a rapid i'ate that the venting orifice mightnot be s'uliicient to allow its escape and eventually a pressure mightbe built up suflicient to rupture the switch tank.

An object of my invention is to provide im provedmeans controlled by apredetermined pressure in the vswitch tank for quickly relieving thepressure.

My invention will be better understood 1 from the following descriptiontaken in conf iiection with the accompanying drawing, and

its scope will be-pointed out iii the-appended claims.

Referring to the drawing, Fig. l is an ele vatioii with parts brokenaway of a switch iiivolving my invention; Figs. A2 and 8 are enlargeddetail cross-sectional views of the discharge pipe of the switch showingthe relief valve and operating mechanism therefor. Y

310 `The switch shown inV l comprises aY closed receptacle vformedby atank l and a -Y cover:V 2 through which extend-'the insulator bushings 3carrying the terminals 4 and the contact operating mechanism, not shown.Y For illustrative purposes only, I have chosen to'show .the switch llofthe explosionchamconnected by a bridging-member 7i to'wliich isconne'ctedithe operating rod 8. `Atene side of casing l0v containingztheswitch operating mechanism yI have shown the vent pipe 11 whichpreferably.-v extendsfrom the switch to avpoint-outside of thebuildingyin which the vswitch is housed.: The ventingy orificecoinmunicating with this pipe is preferably made relativelysmall.'F A

'.IAt Vthe fother side of shown'theve'ntpipe V12 ,which also preferablyis arrangedV to dischargegas and liquid, at a the. casing io'i have eJOHN D. HILLLARD, or scHENEcTADY, newI YORK, Assis/fixiertToenivnniinriiinemitrc,

pointl where itIcan-donodamage; such-as outsideof-ntheY buildingVlwhichhouses the Y switch. Thel orificelby which this pipe com-*municates With-'theiiiteriOr ofthe switchis not restricted -butthe:passageway isnormally closedbya valve fof relatively large size so thatwhen it opens due to excessive pressure within theV sw'itrc'hztank, forexample, due to a breakfdownQ-ora yfailure ofthe switchfthe. pressuremay Vbe, quickly'relieved or `at Vleast .preventedfrom.building upto adangerous value.- VI' have shown the vdischargepipe 12 providedwith: vanintermediate iianged section 13to which vit is .secured as `for` examplehy bOItslLLf` .Section-13 is shown having an inwardly eXtendin'g-flangelin which is formed'the seat for'thevalve 16.' The valve n f is guided bythe ring 17 yconnected tothe seclti'on'l?)V by suitable struts .18 andvis limited in ,its opening movement by thespider 19 ,which is securedtothevalve bythe screw stud 20.V Thevalve isnormally heldv orthr-ustagainst i the seat by toggle mechanism comprising the` Elinks 22f-and23.1- Link 22 pivotally connects .with the aforementioned stud 2O andlink23 isV connected pin31 withlink 22 andby pin a.mutui@ Saraatwhieiiauaisiieia by the Y 'spider25fwhich isboltedfto the upperlend ofthe Sectionll.. Thespider has 'a downward. im?? Y extension 27 whichsupports a screw stop 28 which by engagement with the upper link 23 llimits the amount of overset that the toggle may take. To insure properresetting of the valve after an opening movement and the desiredoversetting of the toggle, I have shown the spring 30 attached to pivotpins 31 and 32 and having the bent end 33 arranged to engage the stud24. It will be seen that the toggle automatically resets itself andiirmlyv holds the valve closed `untilthe pivot pin 3l is pushed pastcenter to allow the `toggleto buckle. Formed in the valve 16 is thesmallcylinder 35 in which slides the piston 36 hav- Vand consequent reseatingof the valve upon predetermined decrease of said pressure.

v In witness whereof, I have `hereunto set my hand this 30th day ofSeptember, 1926; f JOHN nD. HILLIARD.

ing the ro'd 37 passing throughthe vented l screw plug 38 in the upperend 'of the cylinder. VSpring 39 normally holds theV piston down againstashoulder on the cylinder wall forming its seat. The opening leading tothe piston valve 36 is covered by the screen l0 to protect the valve`fromapi-ojected vmass 0f insulating liquid which might cause it to0perate at a point below vthe required static pressure at which it wasset. The pressure at which the piston valve will operate may be variedby adjustment of the screw plug 38. The lower link 22 of the toggle islshown provided with a lateralextension 41 which when pressed withsui'licient force by the r0d37 moves the toggle pin 31 over center andallows'it to bulle. The adjustment is such that the pressures producedin the tank by the normal operation of the switch will not be throughthe restricted orifice in ventv pipe 11. In the event of a break-'downin the switch or other cause of abnormal pressure therein,

the piston valve 36 inresp'ondingto such abnormal pressure will jtripthe toggle and alf low thel large Valve t0v release the `gas and jliquid, thereby preventing ja further risein p pressure.

wVliatIclai-rn 'as V:new and desireto secure by Letters Patent of theUnited States, is `z- *1.V A valve structure adapted for the quickrelief of excessive'pressure in 'a tank comprising means forming a valveseata valve-therelsufficient to cause thev large valve 16.to open, thegas 'formed at such operations escaping v ior,a to' 'Gle for normallkholdin the valve v ge Y g on'the seat, and means carriedvbythe valve fand subject to the pressure withinv the tank c tion retaining the valveon its seat'.

for releasing the toggle. 2. Apparatus adapted for the quick relief ofexcessive pressure in an enclosedA fluid i Ybreak switch comprising avalve seat,'a valve, a toggle for retaining the valve on the seat,

pressure responsive means for tripping the toggle thereby to allow thevalve to open una der the influence of and to relieve the pres-V Y sure,and a spring arranged to effect'thelsubsequent restoration of thetoggle'to the posi- 3. Apparatus adapted for the quick relief of excesspressureinan enclosed uid break .switch lcomprising a lvfalveseat7 avalve kv.for`

